This invention relates to nitropyrazinyl-and nitropyridinyl- substituted piperazin-3-one and hexahydro-1H-1,4-diazepin-5-one compounds used as sensitizers of hypoxic tumor cells to therapeutic radiation. It also relates to the process of preparing such compounds by reaction of substituted piperazin-3-one and hexahydro-1H-1,4-diazepin-5-one compounds with certain specific chloronitropyrazines and chloronitropyridines defined hereinbelow.
At the present time, certain other unrelated compounds are in experimental clinical use as radiation sensitizers. However, these compounds--for example, metronidazole and misonidazole--suffer from the drawback that they also cause neurotoxicity which limits their usefulness. The compounds of the present invention are effective radiation sensitizers, but are believed to have a more favorable therapeutic ratio.